• The more constant voltage supplied to the X-ray tube will give greater radiation quantity and quality.
• A greater number of x-rays are produced when the electron energy is high 
• Increases radiation quality because fewer low-energy projectile electrons pass from cathode to anode to produce low-energy x-rays
• 3 phase power and high frequency generator – the voltage applied across the x-ray tube is nearly constant

Primary Circuit: contains the main power switch, circuit breakers, the autotransformer, the timer circuit, and the primary side of the step-up transformer.

Secondary Circuit: contains the secondary side of the step-up transformer, the mA meter, a rectifier bank, and the x-ray tube.

Filament Circuit: contains the rheostat, a step-down transformer, and the filaments.

After the technologist selects the desired exposure techniques, x-ray production starts by the kVp selected adjusts the autotransformer and determines the number of turns on the secondary side necessary to produce a voltage. The step-up transformer increases this voltage, then travels to the rectifiers. After traveling through the rectifiers, we go back to the autotransformer to complete the rest of this process. The filament circuit draws electricity from the autotransformer, which then travels to the rheostat. From the rheostat, electricity then travels to the step-down transformer. The adjusted current from the step-down transformer then travels directly to the filament located within the focusing cup of the x-ray tube. The current that is created then heats the filament where electrons are boiled off. Finally, the electrons move from cathode to anode to create x-ray photons until the timer circuit terminates.

Components of the X-ray tube: 

• Cathode & anode assemblies
• Tube enclosure
• Rotor & stator
• Protective housing

Cathode: (negative side of X-ray tube) contains filaments and focusing cup. Filament emits electrons when it is heated; made out of tungsten. Focusing cup, focuses the electron beam to the focal spot on the surface of the anode; made up of nickel.

Anode: (positive side of X-ray tube) it conducts electricity and radiates heat and x-rays from the target. The 3 purposes of the anode – electrical conductor, thermal dissipator, and mechanical support. There are 2 types of anodes : stationary & rotating. Stationary made up of tungsten button and rotating made of molybdenum.

Tube Enclosure: maintains a vacuum inside the tube. The purpose of this vacuum is to allow more efficient x-ray production and to long tube life. Because of the amount of heat that is generated, the glass enclosure is made out of pyrex so it can remain undamaged.

Rotor & Stator: Rotor is the rotating portion of the motor and the stator is the stationary part. Rotor is the rotation due to the windings and magnetic fields. The stator converts the rotating magnetic field to electric current.

Protective Housing: guards against excessive radiation exposure and electrical shock.

Function of diagnostic X-ray tubes: to convert electric energy into x-ray photons.

Radioactivity – spontaneous emission of particles and energy in order to become stable

Radioactive Decay – to reach stability, the nucleus spontaneously emits particles and energy and transforms itself into another atom. Results in emission of alpha particles, beta particles, and usually gamma rays.

Isotopes – atoms that have the same atomic number but different atomic mass numbers

“Beta emission occurs much more frequently than alpha emission. Virtually all radioisotopes are capable of transformation by beta emission, but only heavy radioisotopes are capable of alpha emission. Some radioisotopes are pure beta emitters or pure alpha emitters, but most emit gamma rays simultaneously with the particle emission.”

Ionizing Radiation: radiation with enough energy so that during an interaction with an atom, it can remove tightly bound electrons from the orbit of an atom, causing the atom to become charged or ionized

Non-Ionizing Radiation: lower energy on the electromagnetic spectrum. Exits all around us in every day life from multiple different sources. Ex. microwave, UV light from sun

What is the difference between the two types? The way they act on materials such as water, air, and living tissues. Non-ionizing radiation does not have enough energy to remove electrons from atoms and molecules like ionizing radiation does.

Particulate radiation: consists of particles that have mass & energy, and may or may not have an electric charge

2 main types of particulate radiation are alpha particles and beta particles. These 2 types are associated with radioactive decay.

The difference between the two particles is their mass and charge. Alpha particle has 2 protons and 2 neutrons. Its atomic mass unit is approximately 4 and it carries 2 units of positive electric charge. Beta particles have a less atomic mass number. This particles atomic mass is 0 and carries only 1 unit of negative or positive charge, making it a light particle.

Velocity = Frequency ⅹ Wavelength

• Frequency: number of wavelengths that pass a point of observation per second
• Wavelength: distance from any point on the sine wave to the next corresponding point.
• As frequency increases, wavelength decreases
• The shorter the wavelength the higher the frequency
• velocity is a constant
• At a given velocity, wavelength and frequency are inversely related
• As velocity decreases, frequency decreases proportionately

Quantity Symbol	Quantity Term	Unit	Unit Symbol
v	wave speed	meters/second	m/s
􏰁𝛌	wavelength	meter	m
f	frequency	Hertz	Hz

EX. A wave has frequency of 50 Hz and a wavelength of 10 m. What is the speed of the wave?

f 􏰀= 50 Hz
𝛌 = 10 m

v = 􏰁𝛌 ⅹ 􏰃 f

􏰄(10 m)ⅹ(􏰅􏰃 􏰄50 Hz)􏰅􏰀 = 500m/s

Electromagnetic spectrum– the range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies

• 

• The three most important electromagnetic energies in radiologic science are visible light, x- and gamma radiation, and RF (radio frequency).
• Each electromagnetic energy has the same velocity; which is the speed of light
• Speed of light = 3 ⅹ 10⁸ m/s
• Gamma rays and X-rays have the highest energy photon –> only difference between the two are their origin. X-rays come from the outside the nucleus of atoms and gamma rays come from the inside of the nucleus of radioactive atoms
• Wavelength and frequency = inversely related
• Energy of a photon = directly related to frequency
• Radio waves, microwaves, infrared light, visible light, ultraviolet light, x-rays, and gamma rays – these are all members of the electromagnetic spectrum, however, each behaves differently depending on their energy.

Frequency – The number of wavelengths passing a point per second

Wavelength – Distance from one crest to another

Energy – the ability to do work. Energy can be given off in many different forms (potential, kinetic, chemical, thermal, etc)

• The energy of a wave is directly proportional to frequency
• Electromagnetic energy – frequency and wavelength are inversely proportional.
• Electromagnetic Energy calculation – E(Energy) = h(Planck’s constant) x f(Frequency)
• Planck’s constant = 4.15 x 10^-15 eV-sec
• As frequency increases, energy increases